1. Field of Invention
Various embodiments of the present disclosure generally relate to an electronic device, and more particularly, to a feedback system and a method of operating the feedback system.
2. Description of Related Art
Semiconductor integrated circuits may use a feedback control method in which a target value is compared with a previously outputted value and control is performed using the result of the comparison as feedback in order to acquire or maintain a desired output. Typical examples of digital feedback systems include a phase-locked loop circuit, a delay-locked loop circuit, a ZQ calibration circuit, and the like.
In digital feedback systems, a target value signal to be compared with an output signal may vary due to various reasons, in which case a dead zone may appear in the output signal. Accordingly, it is necessary to eliminate the dead zone in order to guarantee an accurate output level. Meanwhile, a phase-locked loop circuit, a delay-locked loop circuit, a ZQ calibration circuit, or the like may be included in a nonvolatile memory device.
Nonvolatile memories include a Read Only Memory (ROM), a Programmable ROM (PROM), an Electrically Programmable ROM (EPROM), an Electrically Erasable and Programmable ROM (EEPROM), a flash memory, a Phase-change RAM (PRAM), a Magnetic RAM (MRAM), a Resistive RAM (RRAM), a Ferroelectric RAM (FRAM), and the like.